Using low-voltage, unregulated DC output power from fuel cells or other unregulated power sources in distributed power systems, particularly for aircraft, is an emerging technology. Current aircraft power system use a centralized power generation system, such as engine driven generators, with typical voltages of 115 VAC or 230 VAC. Emergency backup power sources of the aircraft may use low-voltage batteries.
Fuel cells may be used as auxiliary electric power sources on aircraft to deliver localized and/or peak power. They may also be used as a source of emergency power. However, a fuel cell provides an unregulated DC voltage which varies with the load by as much as 50% from low-load to full-load operation. Therefore, fuel cells alone are not a valid substitute for the engine driven generators used in current aircraft since they are incapable of providing various levels and configurations of DC and AC voltages.
One solution for adapting a fuel cell to generate various levels and configurations of DC and AC voltages includes the use of DC/DC converters and inverters. One such solution is shown in the U.S. Ser. No. 13/945,511, filed Jul. 18, 2013, and entitled “AIRCRAFT UNIVERSAL POWER CONVERTER.” In order to meet various system requirements, such as those mandated for use by the aircraft industry, electromagnetic interference (EMI) filters are typically required for each converter. However, the size and weight of the power system may undesirably increase with the addition of each EMI filter.